System, method, and apparatus for power limited sky diving wind tunnel drive train/fan

ABSTRACT

A flight simulator having a wind tunnel with a vertical flight chamber and a second vertical chamber communicatively coupled thereto via air flow conduits. A nacelle disposed within the second vertical chamber includes a fan and a ratio gearbox connected to the fan. A motor is disposed remote from the nacelle for powering the fan via a jackshaft and the ratio gearbox. A variable frequency drive responsive to a control signal from a programmable logic controller regulates the speed of the motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/373,608 filed on Apr. 2, 2019, which claims the benefit of U.S.Provisional Patent Application No. 62/651,697 filed Apr. 2, 2018, theentire disclosures of which are hereby incorporated by reference for allpurposes as if being set forth in their entirety herein.

FIELD OF THE INVENTION

The application relates to the field of wind tunnels. More particularly,the application relates to systems, methods, and apparatus for skydiving wind tunnels having improved performance, reliability, safety,energy efficiency, reduced nacelle footprint and/or reduced fanrequirements.

BACKGROUND

Wind tunnels are used in testing of aircraft, surface, ground, andsubsurface vehicles, launch vehicles, buildings and other fixedstructures, training systems, as well as for recreational use andamusement.

Significant power resource requirements, inadequate safety mechanisms,and large component structural size as well as increased componentnumber requirements, have led to wind tunnel systems having a largefootprint and that are extremely costly to operate and maintain.Further, existing systems are energy inefficient, potentially hazardous,difficult to commission, and lacking in performance. Alternativesystems, methods, and apparatus for alleviating one or more of the aboveproblems are desired.

SUMMARY

In an embodiment of the present disclosure, there is provided a morereliable and safer drive train and fan for vertical sky diving windtunnels. To reduce the power and enhance reliability, a ratio gearboxwhich directly connects to a single fan, is provided within the nacelleand replaces the motor within the nacelle. Locating the motor in alocation outside of the wind tunnel not only reduces the size of thenacelle, but also provides for greater accessibility. Configuration of aratio gearbox within the nacelle also reduces the horsepowerrequirements for both the motor and the variable frequency drive.Controls are provided that run the motor within a defined speed rangeand further eliminates the need for supplemental motor cooling.

The system is further configured with a single fan, nacelle and motorsuch that if electrical power to the system is lost, the single fan hassufficient mass and inertia in relation to the wind tunnel such that therotation rate is reduced at a sufficiently slow level to enable a flyer(person or user) to be lowered so as to avoid an abrupt drop and therebyreduce the likelihood of injury. Multiple nacelles, motors and fanswithin a sky wind tunnel require more power, are more difficult tomaintain, and do not have the fan mass and inertia to maintain air speedto slowly lower a flyer upon the loss of electric power. Embodiments ofthe present disclosure eliminate one or more of the above-identifiedproblems while providing enhanced system operation and control and withreduced power requirements.

In an embodiment there is disclosed a drive train for a wind tunnelhaving a nacelle housing with a fan and a fan hub assembly. The drivetrain comprises: a ratio gear box directly connected to the fan; and amotor disposed remote from the nacelle for powering the fan via ajackshaft and the ratio gearbox. In an embodiment, the wind tunnel has asingle fan and single hub assembly. The jackshaft operatively connectsthe motor and gearbox.

In an embodiment, a system for controlling a wind tunnel having a fanand nacelle comprises a ratio gearbox housed within the nacelle of thewind tunnel and directly connected to the fan; a motor disposed remotefrom the nacelle for powering the fan via a jackshaft and the ratiogearbox; and a variable frequency drive positioned remote from the windtunnel and configured to regulate the speed of the motor within a rangesufficient to negate supplemental external cooling of the motor.

The system further includes a lubrication system disposed remote fromthe nacelle and coupled to the ratio gearbox for controllably dispensinglubricant thereto.

In an embodiment the variable frequency drive may include anelectronically controllable switch for selectively disconnecting powerto the motor in response to a user operation. The switch is configuredas a small disconnect switch of reduced size and operates toadvantageously replace large high power disconnect switches typicallyrequired of conventional systems.

In an embodiment, the variable frequency drive includes an electroniccircuit with inherent redundancy that is connected to a switch forvirtually disconnecting power to the motor in response to user operationof the switch. In an embodiment, the switch is configured as a small twopole toggle switch of reduced size and operates to advantageouslyreplace large high power disconnect switches typically required ofconventional systems having a relatively large motor.

In an embodiment, a simulator comprises: a wind tunnel chamber; anacelle disposed within the wind tunnel chamber and including a ratiogearbox directly connected to a fan; a motor disposed remote from thenacelle for powering the fan via a jackshaft and the ratio gearbox; anda variable frequency drive positioned remote from the wind tunnelchamber and configured to regulate the speed of the motor to therebymaintain a temperate of the motor within predetermined range that issufficiently low to obviate the need for supplemental external cooling.

In an embodiment, a simulator comprises: a wind tunnel chambercomprising a first vertical flight chamber and a second vertical chamberremote from the first vertical flight chamber and communicativelycoupled thereto via air flow conduits; a nacelle disposed within thesecond vertical chamber of the wind tunnel chamber and including a ratiogearbox directly connected to a fan; a motor positioned remote from thenacelle and wind tunnel chamber for powering the fan via a jackshaft andthe ratio gearbox; and a variable frequency drive positioned remote fromthe wind tunnel chamber and configured to regulate the speed of themotor to thereby maintain a temperate of the motor within apredetermined range. In an embodiment, a programmable logic controlleris responsive to one or more environmental parameters for generating acontrol signal to the variable frequency device to controllably adjustmotor speed.

In an embodiment, a lubrication system is located remote from the windtunnel chamber and coupled to the ratio gearbox for controllablydispensing lubricant thereto.

In one aspect, the programmable logic controller is responsive to one ormore of temperature, pressure, leakage, and flow parameters output fromthe lubrication system for generating a control signal to the variablefrequency device to controllably adjust motor speed.

In an embodiment, the variable frequency drive is an IEEE 519 compliantVFD which controllably adjusts at least one of frequency and voltageapplied to said motor to operate said motor at one of two predeterminedRPM rates.

BRIEF DESCRIPTION OF THE DRAWINGS

Understanding of the present invention will be facilitated byconsideration of the following detailed description of the preferredembodiments of the present invention taken in conjunction with theaccompanying drawings, in which like numerals refer to like parts and inwhich:

FIG. 1 is an exemplary diagram illustrating components of a closedarchitecture implementation according to an embodiment of thedisclosure.

FIG. 2 is an exemplary schematic diagram illustrating components of thesystem including the gearbox, jack shaft, motor, fan, and variablefrequency drive (VFD) according to an embodiment of the disclosure.

FIG. 3 is an exemplary partial cross-section view illustratingcomponents according to an embodiment of the disclosure.

FIG. 4 is a more detailed exemplary partial cross-section view of theratio gearbox, fan, and jack shaft components according to an embodimentof the disclosure.

FIG. 5 is an exemplary diagram of a lubrication oil system according toan embodiment of the disclosure.

FIG. 6 is an exemplary connection diagram between electronic devicesaccording to an embodiment of the disclosure.

FIG. 7A is a schematic diagram showing instrumentation and controlcomponents associated with the wind tunnel system and architectureaccording to an embodiment of the disclosure.

FIG. 7B is a schematic diagram showing electronic and control componentsassociated with the lubrication oil system according to an embodiment ofthe disclosure.

FIG. 8 is an exemplary diagram of a PLC control system and userinterface according to an embodiment of the disclosure.

FIG. 9 is a schematic diagram showing instrumentation and controlcomponent interconnects associated with the wind tunnel system andarchitecture according to an embodiment of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the figures and descriptions of the presentdisclosure show, by way of illustration, specific embodiments in whichaspects of the invention may be practiced. It is to be understood thatthe various embodiments illustrate particular features, structures, orcharacteristics described herein in connection implementation of a drivetrain, system, and method for making such drive train and system,without departing from the scope of the invention.

Reference will now be made in detail to the present exemplaryembodiments of the disclosure, examples of which are illustrated in theaccompanying drawings. Wherever possible, like reference numbers will beused throughout the drawings to refer to like parts.

According to an aspect of the present disclosure, a sky diving tunneldrive train/fan system is implemented with only a single fan (vis-a-vismultiple fans) that provides increased wind tunnel performance, anddecreased horsepower, which reduces utility costs. The system accordingto the present disclosure, by implementing a lower horsepower, alsoeliminates the need for ground fault protection and concomitantpotential nuisance loss of utility power. The system of the presentdisclosure possesses a rated horsepower to produce sufficient torquewhen the motor runs above a given rated frequency (e.g. 60 hertz),thereby producing an optimized (highest) wind speed under the specifiedload.

Referring now to FIG. 1, in conjunction with FIGS. 2 and 3, there isshown a system 100 for directing air flow within a vertical sky divingwind tunnel, according to an embodiment of the present disclosure. FIG.1 illustrates an exemplary closed loop configuration 100 comprising asingle fan and hub assembly 110 (FIG. 2) housed within a cylindrical fansection 220 and connected via air flow duct 240 to wind tunnel flightchamber 250. Flight chamber 250 is configured to accommodate one or moreskydivers or players within the chamber. Fly door 255 providesingress/egress to flight chamber 250. Grid floor 245 is configured tosupport the weight of the player(s) entering the chamber while allowingair flow through the floor in the direction of arrow A₁ with forcesufficient to controllably elevate the one or more players from floor245 via control system 270 which is operatively connected to the motorand single fan and hub assembly. Flight chamber 250 terminates atceiling grid 252 connected to diffuser section 260. Floor grid 245 andceiling grid 252 provide vertical boundaries for each of the playerswithin chamber 250. Air flow duct 210 coupled to diffuser section 260conveys via fan diffuser 230 air flow in the direction of arrow A₂through to fan section 220 for circulation/re-circulation through theclosed loop system. Supports 280 a and 280 b provide structural supportfor the wind tunnel flight chamber portion while support 280 c providesstructural support for the fan diffuser and fan section. A motor pithatch 248 located on platform 205 provides access to the motor andassociated equipment.

To reduce power and enhance reliability, a ratio gearbox 130 (FIG. 2)which directly connects to single fan and hub assembly 110, is providedwithin nacelle or housing 120 (FIG. 3) and replaces the motor that wouldotherwise be located in the nacelle. FIG. 2 illustrates theconfiguration of key components of the drive train and fan and hubassembly according to an embodiment of the disclosure. As shown, ajackshaft 150 connects external motor 140 to the ratio gearbox 130. Thisdesign enhances the efficiency of the wind tunnel as it reduces the sizeof the nacelle and eliminates the need for large electrical conductorcircuitry connecting the motor to be housed within the nacelle.Jackshaft 150 is smaller in diameter than the overall diameter of theelectrical circuit conductors. The electric circuit conductors consistof parallel conductors within multiple conduits 20 that connect to themotor. Reducing the size of the nacelle and the obstruction between thenacelle and the wall of the wind tunnel lowers the drag on the air andincreases the overall system efficiency.

In an embodiment there is disclosed a drive train for a wind tunnelhaving a nacelle housing with a fan and a fan hub assembly. The drivetrain comprises the ratio gear box 130 directly connected to the fan 112and jack-shaft 150 that connects the gearbox to the motor 140. Thedesign uses a standard horizontal motor located outside of the windtunnel. The horizontal motor provides power to the fan via the jackshaftand the ratio gearbox. Larger diameter wind tunnels requiring morehorsepower, could have additional fans, each with a dedicated blade hubassembly, jack shaft and motor as shown in FIG. 2. According to anembodiment of the present disclosure, there may be one VFD per motor asshown in FIG. 2, or one VFD for multiple motors.

According to an embodiment of the disclosure, locating the motor 140remote from (outside of) the wind tunnel provides greater access to themotor and enables use of a standard horizontal motor (e.g. 450 HPmotor), rather than a customized, more expensive, non-standard invertedvertical motor, which may also require a drive end thrust bearing. Theuse of standardized units for the ratio gearbox with a drive end thrustbearing and a standard horizontal motor increases the system reliabilitywhile reducing the overall required horsepower to produce the same windspeed by about 25 percent (e.g. from 600 HP to 450 HP), thereby reducingboth the initial cost as well as the operating costs

Still referring to FIGS. 2 and 3, use of a ratio gearbox 130mechanically multiplies the motor 140 output torque, which is the forceof rotation, at any given horsepower as can be determined by thefollowing equation. In a preferred embodiment, ratio gearbox 130 isimplemented as a 2.5:1 ratio gearbox, with an 1,800 revolutions perminute (RPM) motor 140 to run the fan 112 at 720 RPM provides a torquedetermined as:

TORQUE=(5252×HP)/RPM

In an advantageous embodiment, use of the 2.5:1 ratio gearbox incombination with programming of the system to always operate at above aselect RPM value, eliminates the need for a costly supplemental externalcooling system for the motor.

According to an advantageous embodiment, a variable frequency drive(VFD) 160 is electrically coupled to motor 140 via motor branch circuitcables 20 (FIG. 2) which vary the frequency and/or voltage of the motorto turn the device at different speeds. The system is configured tooperate at either 0 RPM or above 500 RPM, but never in between theseconditional values. A VFD, when powering variable torque loads, whichincludes fans, enables the system's horsepower to be reduced by the cubeof the RPM while the torque is reduced by the square of the RPM. Whenthe motor torque is reduced by 20%, in response to reduced torque neededat the higher speeds, the horsepower will be reduced by 51%.

According to an embodiment of the disclosure, each of the mechanicalsystem components, including the fan hub 114, are designed with nosingle latent points of failure through use of redundant instruments andcontrol devices or equivalent SIL rated relays. As shown in FIG. 4, thesystem of the present disclosure includes a plurality of fasteners suchas bolts 116 connected through the fan hub 114 to the gearbox shaft, incontrast to commonly used press-fit connections between the fan hub anddrive shaft. Jack shaft 150 is directly coupled to ratio gearbox 130 andmotor 140 via respective couplers 152, 154 (FIG. 2, 4) fixedly connected(e.g. bolted) thereto.

In an embodiment, a system for controlling a wind tunnel having a fanand nacelle comprises a ratio gearbox housed within the nacelle of thewind tunnel and directly connected to the fan. Motor 140 is disposedremote from the nacelle for powering the fan 112 via jackshaft 150 andthe ratio gearbox 130. A variable frequency drive 160 located remotefrom the wind tunnel is configured to regulate the speed of the motorwithin a range sufficient to negate supplemental external cooling of themotor. A programmable logic control system 270 is programmed to onlygenerate control signal to VFD 160 to run the motor within a definedspeed range, thereby eliminating the need for supplemental motorcooling. FIG. 8 shows an exemplary illustration of the PLC controlsystem and user interface (HMI) 270 showing the operator console anddisplay 272 for displaying notifications, alerts, status, operatorcontrols, and the like. A potentiometer control 274 is provided toenable user selection and control of the motor speed. E-stop selector276 is also provided on the console display.

According to an embodiment of the disclosure, the system is furtherconfigured with nacelle that has a jackshaft for a single fan connectedto a single motor via a jackshaft motor such that if electrical power tothe system is lost, the single fan's hub has sufficient mass and inertiain relation to the wind tunnel such that the rotation rate is reduced ata sufficiently slow level to enable a flyer (person, player, or user) tobe lowered so as to avoid an abrupt drop and thereby reduce thelikelihood of injury.

In an embodiment, the system is implemented via a standard horizontalmotor located outside of the wind tunnel. The horizontal motor providespower to the fan via the jackshaft and the ratio gearbox. The horizontalmotor is controlled by the VFD 160, which is implemented as an ultra-lowharmonic Variable Frequency Drive useful in buildings where the windtunnel is the primary load on the utility service entrance in compliancewith industry and utility recommended standards for harmonics, IEEE519-2014 IEEE Recommended Practice and Requirements for Harmonic Controlin Electric Power Systems.

In an embodiment, PLC 270 may be software enabled to communicate withthe IEEE 519 compliant VFD for controlling motor speed via Ethernet orwires. In an embodiment, an ultra-low harmonic variable frequency drive(VFD) that uses front end rectifier with insulated gate bipolartransistors (IGBTs) may be used as an alternative to a diode based VFD.The IGBTs are controlled to minimize harmonics (electrical noise) on thesupply power distribution system, enabling the use of the VFD inbuildings where the wind tunnel is a large or majority portion of thetotal building load. Because of the size of the motor (e.g. 500 HP) theuse of a standard 6 pulse diode front end VFD may create electricalproblems within the venues where such a fixed system wind tunnel wouldbe installed. Alternative 12 and 18 pulse VFDs that provide harmonicattenuation use phase shifting transformers and require more space maybe used but are predicted to be less efficient. In an embodiment, anACS-880-37 VFD may provide high efficiency and due to its reduced sizecan be installed in a relatively small equipment room or smallelectrical room.

In an embodiment a system for controlling a wind tunnel having a fan andnacelle comprises a ratio gearbox housed within the nacelle of the windtunnel and directly connected to the fan. A motor is disposed remotefrom the nacelle for powering the fan via a jackshaft and the ratiogearbox; and a variable frequency drive that has a Select Torque Off.According to an embodiment, the system utilizes within a VFD a SafeTorque Off (STO) functionality that selectively prevents the VFD fromgenerating torque in the motor. It ensures that no torque generatingenergy continues to act on the motor and that the motor cannot bere-started until the STO is removed. Hence once activated, the motorwill not turn after it has come to a stop. Implementation of the STOfeature enables the Safe Torque Off Control Station, which allows atechnician to safely inspect the fan blades and other mechanicalcomponents, with the illumination of a lighted display (e.g. green light(safe), red light (not safe)). The STO feature may also be used after anemergency stop (E-STOP), thereby enhancing the overall safety of thesystem.

In an embodiment a system for controlling a wind tunnel having a fan andnacelle comprises a ratio gearbox housed within the nacelle of the windtunnel and directly connected to the fan; a motor disposed remote fromthe nacelle for powering the fan via a jackshaft and the ratio gearbox;and a variable frequency drive that has redundant emergency stoppushbuttons. Hard wired, redundant emergency stop pushbuttons, one onthe console and the other at the wind tunnel door, enables the operatorat the console or flight instructor at the door to perform a controlledstop of the wind tunnel. The VFD will slowly lower the wind speed as themotor is stopped while the PLC illuminates a RED LED strip around thebottom of the wind tunnel flight chamber. After the time delay, set on asafety (SIL rated) relay, another safety relay will initialize the STO.An added benefit of this design is that if anyone removes the inspectionhatch door for the blades, without switching the STO to the “ON”position, the PLC will initiate an equipment emergency stop which willactivate the STO function after the time delay set in the safety relay.By way of example only, the emergency stop functionality may beimplemented by an operator at the flight chamber door or at the controlconsole.

In another embodiment, responsive to a signal from the control panel, alubrication oil system 170 maintains the flow and temperature oflubrication oil to and from the gearbox 130 using an oil pump 1718 (FIG.5) and a lube oil fan and instruments controlled and monitored by PLC270 via combination starters. FIG. 5 is a detailed illustration of thelubrication oil system 170. As shown in FIG. 5, a lube oil tank 1708(e.g. 20 gal. capacity) provides a supply of lube oil via supply conduit1736 to gearbox 130. Return conduit 1726 carries the oil returned fromgearbox 130. Pump 1718 (e.g. 3 HP pump and motor at 15 GPM and 35 PSI)and cooling unit 1720 (e.g. 31,000 BTU/Hr lube oil cooling unit) providecirculation of the cooling lube oil. The lubrication system is housed ona skid and comprises a base 1700 containing the system components. Thesystem includes pressure 1702 and temperature 1704 gauges, valves 1714(bypass flow balancing valve), 1716 (check valve), and 1728 (gearboxflow balancing valve), and switching devices 1712 (low oil pressureswitch), 1722 (cooler fan switch), 1724 (oil high temp switch), 1732(low flow switch), 1734 (flow meter and high flow switch), and 1738 (oilleak switch) to regulate oil flow according to one or more operatingconditions associated with the lube oil system. Tank 1708 includes oillevel gauge, drain plug and magnetic chip detector 1706 and airvent/filter 1710. Oil strainer 1730 operates to remove system debris andcontaminants from the circulating fluid.

In an embodiment there is disclosed a system for controlling a windtunnel having one or more nacelles for each fan and nacelles comprisinga ratio gearbox housed within the nacelle of the wind tunnel anddirectly connected to the fan; a motor located remote from the nacellefor powering the fan via a jackshaft and the ratio gearbox; and avariable frequency drive (VFD) or variable frequency drives positionedremote from the wind tunnel and a control console consisting of aprogrammable logic controller (PLC), a Human Machine Interface (HMI) anda potentiometer that enables the wind tunnel operator to run the fan atRPMs above the RPM for which the motor does not require externalsupplemental cooling. In an embodiment, for implementation of a 2.5:1ratio gearbox, when the fan runs at 200 RPM the motor runs at 500 RPM.This motor rotation eliminates the need for external supplementalcooling of the motor, which is an added benefit of using an 1,800 RPMmotor, but does not constitute sufficient wind speed to enable flight inthe tunnel. The PLC is configured to operate to only send RPM values tothe VFD that are at or above 500 RPM. The VFD is configured to only runbetween 500 RPM and 1915 RPM and will require the operator to bring theair speed in the tunnel to 40 miles per hour (MPH) when an operatorturns the tunnel off and on from the HMI. Afterwards, the operator canincrease the air speed using the potentiometer in a range between 40 MPHand 157 MPH.

The drive train and single fan implementation of the present disclosureprovides a design applicable for multiple utility and motor voltages andis not limited to small sky diving wind tunnels. For small sky divingwind tunnels, the reduced horsepower enables use of a 480 voltelectrical service which provides the following benefits:

-   -   a. Eliminates the NEC requirement for ground fault protection        and the potential for nuisance tripping associated with ground        fault protection;    -   b. Enables selection of overcurrent protective devices which        reduces the incident energy level at the electrical equipment        caused by arc flashes, thus reducing the electrical hazard;    -   c. Using an active front end variable frequency drive that        complies with IEEE 519-2015 versus a standard 6 pole diode        passive find end VFD eliminates harmonic problems within        building where the wind tunnel is the major load.

With a variable frequency drive for a variable torque load such as thewind tunnel fan, the torque is proportional to the square of the speedwhile horsepower is proportional to the cube of the speed. The systememploys an easily maintainable and replaceable horizontal motor locatedoutside of the wind tunnel. The motor connects to a right angle gearboxusing a jackshaft, which has less cross sectional area than the 480 Voltor higher voltage motor branch circuit for a vertical motor in thenacelle. The right angle gearbox is configured to multiply the torqueand reduce the size of the motor, and connects to the fan hub. Thesystem achieves a lowest tunnel operating airspeed by configuring of theVFD, and guarantees that the motor will never run below the speed neededto keep the motor cool without supplemental cooling, thereby allowingthe use of a standard, invertor duty, open drip proof motor. A gearboxratio is selected that limits the fan RPM to the motor's top RPM,reached at a frequency slightly higher than 60 hertz. This RPM existswhen the torque that the drive train can produce is lower than thetorque required for the fan to deliver the maximum designed power forthe wind tunnel. This design guarantees that an operator cannot operatethe tunnel to air speeds greater than intended by the design of thesystem. Cooling and lubricating the gearbox is achieved using an oilpump and cooling fan and tank located outside of the wind tunnel, andthereby provides for easy maintenance.

With further reference to the drawings of FIGS. 1-9, and in particularto FIGS. 6, 7 and 9, there are shown interconnected components of apower limited, sky diving wind tunnel drive train and system accordingto aspects of the present disclosure. Components include:

-   -   1) 480 Volt, IEEE Compliant, voltage source, variable frequency        drive 160 with integral line side disconnect switch 165, current        limiting fuses and safe torque off (STO); or        -   medium voltage (>1,000 Volts) voltage source, variable            frequency drive with: an active or passive front end;            integral line side disconnect switch and contactor; output            disconnector; and integral DC flux or injection braking or            DC chopper braking, with external breaking resistors.    -   2) 460 Volt, open drip proof, horizontal, invertor duty,        Induction motor or a 4,000 Volt, horizontal, invertor duty,        induction motor.    -   3) Jack shaft and couplings between the motor outside of the        wind tunnel and the gearbox with the nacelle of the wind tunnel.    -   4) Right angle gearbox that connects to the fan and is sized to        limit the speed of the fan to the desired safe maximum speed and        handle the upward thrust of the fan and the downward weight of        the fan.    -   5) Fan hub to gearbox coupling with interference fit and bolted        connection for reliability.    -   6) Lube oil pump and fan system that are located outside of the        nacelle for easy maintenance, have instrumentation to protect        the gearbox and provide alerts for potential problems within the        gearbox and enables changing the oil from outside of the wind        tunnel.    -   7) Instrumentation and control system to provide system        integrity and operator interface    -   8) Control Console with HMI operator screen, safety relays and        e-stop.

System Integration includes i) sizing the motor and gearbox to producepower that can provide but cannot exceed the power to handle the windtunnel load resulting from a flyer or flyers within the wind tunnel at adefined maximum air speed; ii) using a fan with the inertia that willenable the fan to keep turning and producing sufficient air speed tosafely lower the flyer or flyers, upon the unexpected loss of electricalpower to the system; iii) operating the wind tunnel at a wind speed thatis safe for flyers (users) to enter and exit the wind tunnel and thatdoes not produce lift while operating the motor at an RPM whicheliminates the need for external cooling of the motor.

The following system implementation description and functionality isfurther provided by way of non-limiting example.

With reference to the drawings, the control system component(s) mayutilize a programmable Logic Controller (PLC) 270 (FIG. 6) fornon-safety controls and functions and two safety relays with the “SafeTorque Off” function in the Variable Frequency Drive (VFD) 160 toprovide Safety Integrity Level (SIL) 3 rated equipment maintenancecircuits. An operator interface that monitors and allows operator inputfor VFD speed control, equipment and tunnel monitoring, and alert statusmay be implemented as a Panelview-800 Touchscreen or other Human MachineInterface and for alarm data logging.

FIG. 7A is a schematic diagram showing the instrumentation and controlcomponents of the window tunnel system and architecture disclosedherein, along with temperature, pressure and vibration sensors andswitching elements, safe torque off components, and emergency stop(E-STOP or ES) controls which, when connected to the console PLC 270shown in FIG. 6, provides safe, reliable, and efficient operation of thewind tunnel. FIG. 7B is a more detailed schematic diagram showingelectronic and control components associated with the lubrication oilsystem shown in FIG. 7A. The following components are identified in FIG.7A as follows:

pressure differential switch - 5401 pressure switch - 5402 safe torqueoff for VFD - 5501 temperature sensor - 5101 temperature switch - 5403vibration sensor - 5301 position switch for door/hatch access - 5404 oilleak sensor - 5601 hand switch - 5701 position indication control - 5702

FIG. 9 is a schematic diagram similar to that of FIG. 7A and showinginstrumentation and control component interconnects associated with thewind tunnel system and architecture according to an embodiment of thedisclosure, including junction box (JB) and pull box (PB) connections,panel board connections, ground wire to gear box 9501, and lube oil pumpmotor m1 and lube oil fan motor m2 connections.

In an embodiment, an uninterruptable power supply in the control powerwill provide 2 minutes of 120 Volt power for the control system afterthe loss of normal building power. There are no backup power systems forthe wind tunnel's drive/motor and lube oil systems. The wind tunnel fanhas sufficient inertia so that it will provide enough wind for fiveseconds, to lower a flyer down slowly, after the loss of the normalpower system.

In an embodiment, a 500 HP, 1800 RPM, 460 Volt, horizontal, open dripproof motor 140 (FIGS. 2 and 3) powers the wind tunnel fan through ajack shaft 150 that connects to a 2.5:1 right angle gearbox 130 in thenacelle 120. The motor is located in the equipment pit or equipmentroom. In order to provide adequate cooling within the motor without anexternal supplemental fan, the VFD is configured so as never to run themotor between 0 RPM and 500 RPM.

The VFD may be implemented as a 500 HP, 480 Volt, IEEE 519 Compliant,active front end, voltage source variable frequency drive with limitedbraking capability. In an embodiment, the VFD is located remote from thenacelle and motor, preferably in a facility electrical room or equipmentroom. The 500 HP motor can run at speeds between 500 RPM (nominal windspeed of 40 miles per hour) and 1,915 RPM (nominal wind speed of 157miles per hour) based on the position of a potentiometer on the PLCcontrol console 270 from the limit set in the VFD and the HMI. The motorRPM rate of change is configurable and may be set during commissioning.A password protected HMI screen enables the operator to set certainoperating parameters, such as maximum wind tunnel air speed.

An LED lighting system may be implemented within the system to providemultiple (e.g. four (4)) user defined and one (1) Emergency scene usingLED strips mounted on the wind tunnel glass. The LED lighting systemincludes a lighting control panel, located in the equipment pit orequipment room, and multiple (e.g. five (5))—12 V DC LED strips fed fromClass 2 Power Supplies. One of the Class 2 Power Supplies for the 12 VDC Red LED Strip is powered from the UPS in the control console. In anembodiment, the LED lighting system includes a lighting control panel,located in the equipment pit or equipment room, and multiple (e.g. four(4))—24 V DC LED strips fed from Class 2 Power Supplies. One of theemergency scene 12 v Class 2 Power Supply in the control console for the12 V DC Red LED Strip is powered from the UPS in the control console

A utility power meter, such as a PowerSmart Advanced meter, isconfigured to measure the utility power source's voltage (volts), powerconsumption (KWh), power demand (KW), total harmonic distortion (THD)and current harmonic distortion (TDD). The meter may be configured toretain these values for up a predetermined time period (e.g. 72 days).The meter is independent and does “not” connect to or communicate withthe PLC Control System. The meter may include a Modbus TCP/IPcommunication via an Ethernet network connection. The meter may belocated in the electrical room or the equipment room.

Tunnel Operation

In an embodiment, the following facility conditions are required before“turning on” the wind tunnel system of the present disclosure:

-   -   a. A nominal 480 Volt, three phase (30) power is on the input        terminals of the VFD.    -   b. 480 Volt, 30 Power is on the line side terminals of the lube        oil pump 9101 and lube oil fan 9201 combination starters and        when applicable the equipment pit exhaust fan 9301 combination        starters. The combination starters are located in the accessible        electrical room or equipment room.    -   c. 120 Volt, 1Ø Power is on the terminals of the Control Console        adjacent to the wind tunnel and if provided the lighting control        panel.    -   d. The building fire alarm system is not in alarm.    -   e. The “Safe Torque Off” 5501 Switches in the Equipment Pit and        near the Wind Tunnel Hatch Door are in the off position and        their red pilot lights are illuminated.    -   f. The Emergency Stop Pushbutton on the control console and at        the Flight Chamber door are in the non-stop position, pulled        out.

The following occurs after the above conditions are met:

-   -   a. The HMI on the control console will display the Main Screen        with the on/off selector switch, which will be in the off        position.    -   b. The VFD performs system checks and magnetizes its DC bus.        This will take approximately 10 seconds. If the VFD does not        detect faults, the VFD closes its “Ready” contact.    -   c. When the VFD Ready Contact is closed and all wind tunnel        hatch doors are closed or hatch panels are in place, the HMI        displays an On/Off Selector Switch, which will be in the “OFF”        position, “Wind Tunnel Off”, the Motor RPM and Wind Speed (MPH).

From the control console, a Trained Operator can “turn on” the windtunnel by moving the On/Off Selector Switch on the HMI to the “On”position. The PLC will do the following:

-   -   a. Closes a PLC DO contact within the 24 Volt AC run circuit of        the Gearbox Lube Oil Pump's motor's combination starter. The PLC        monitors an auxiliary contact in the motor starter.    -   b. Closes a PLC DO contact within the 24 Volt AC run circuit of        the Equipment Pit Exhaust Fan's motor's combination starter. The        PLC monitors an auxiliary contact in the motor starter. This        does not apply to locations with Equipment Rooms.        -   i. Closes a PLC DO contact within the 24 Volt AC run circuit            of the Lube Oil Fan's motor's combination starter when            “both” the Lube Oil Pump Starter's auxiliary contact is            closed and Normally Closed Lube Oil High Temperature Switch            1724 opens. The PLC will keep the Lube Oil Fan motor running            for five minutes after the Temperature Switch 1724 closes.            The PLC monitors an auxiliary contact in the motor starter.    -   c. The PLC monitors the Gearbox Normally Closed Lube Oil Low        Flow Switch 1732 and Normally Closed Lube Oil Low Lube Oil        Pressure Switch 1712. When “both” switches open, indicating that        there is adequate oil flow and pressure, the PLC closes the        “Running” DO which connects to the VFD Start/Stop DI.    -   d. “Wind Tunnel On” replaces “Wind Tunnel Off” on the HMI.    -   e. An Optional Fly Time Stopwatch appears on the HMI screen with        four pushbuttons providing the following Fly times:        -   i. Button 1—Set at 60 seconds        -   ii. Button 2—Set at 90 second        -   iii. Button 3—Set at 120 second        -   iv. Button 4—Set at time in seconds entered on the HMI.            -   Pressing one of the buttons sets the stopwatch. The                stopwatch automatically runs down to 0 seconds unless                reset to another time by pressing any one of the above                buttons.    -   f. The VFD increases the motor speed to the wind speed set by        the position of the potentiometer. The trained operator can        control the wind speed by changing the position of the        “Potentiometer”. The VFD changes the motor RPM in response to        changing the position of the “Potentiometer”. The HMI displays        the motor RPM.    -   g. The PLC monitors a VFD AO. The PLC uses values from pressure        5401 and temperature 5101 instruments, and a formula to        calculate the wind speed. The HMI displays the wind speed in        MPH.    -   h. The Venue's Trained Operator and Instructor are responsible        for the safety of the flyer in the tunnel. They are responsible        for setting the proper wind speeds based on the size and weight        of the flyer or flyers using the potentiometer, by continuous        communication between them using hand signals, and by        continuously observing and controlling the movement of the flyer        within the wind tunnel.

From the control console, an operator can “turn off” the wind tunnel bymoving the “Selector Switch” to the “Off” position on the HMI.

-   -   a. “Wind Tunnel Off” replaces “Wind Tunnel On” on the HMI.    -   b. The VFD brings the motor to 0 RPM following the Normal Stop        Ramp of 25 RPM per second. The Normal Stop Ramp speed and        profile may be set during initialization/commissioning of the        device.    -   c. After expiration of a select time interval (e.g. five (5)        minutes), the PLC delivers an electronic signal to open the DO        contact within the 24 Volt AC run circuit of the Gearbox Lube        Oil Pump's combination starter.    -   d. For locations with equipment pits, after expiration of a        given time interval (e.g. twenty (20) minutes) the PLC delivers        an electronic signal to open the DO contact within the 24 Volt        AC run circuit of the Equipment Pit Exhaust Fan's combination        starter.

Emergency Stops

A. Category 0 Emergency Stop

-   -   a. The following will cause a Category 0 emergency stop.        -   i. Loss of Utility Power        -   ii. Opening the “Wind Tunnel” Service Entrance Disconnect            Switch.        -   iii. Opening the Main Input Switch on the VFD        -   iv. Turning a Safe Torque Off Switches to the “On Position”    -   b. The HMI will display a “VFD Fault” or “Safe Torque Off” and        either:        -   i. The PLC will close a contact illuminating the Red LED            Strip. Or        -   ii. The PLC will send a signal to the DMX module in the LED            Lighting System, which will illuminate Red LEDs.            -   The facility may provide emergency lighting and                illuminated egress signs, if utility power is lost.    -   c. “Wind Tunnel Fault” replaces “Wind Tunnel On” or “Wind Tunnel        Off” on the HMI.    -   d. If Facility power is also lost, the Lube Oil Pump and        Equipment Pit Exhaust Fan will turn off and the HMI will shut        off after the expiration of a given time period (e.g. 2        minutes).    -   e. After utility power returns or the Safe Torque Off switches        are placed in the “on” position, the “Reset” pushbutton will        appear on the HMI.    -   f. Press the “Reset” pushbutton on the HMI and follow Section        II-C to restart the wind tunnel.    -   g. The “Safe Torque Off” control stations have provisions for        “lock out/tag out” and Red (Not Safe) and Green (Safe) pilot        lights. Refer to Section X.

B. Category 1 Emergency Stop

-   -   a. The following will cause a Category 1 Emergency Stop.        -   i. Pressing the E-Stop Pushbutton on the Control Console        -   ii. An equipment malfunction or an instrument alarm            condition.        -   iii. Activation of the building's fire alarm system    -   b. “Wind Tunnel Fault” replaces “Wind Tunnel On” or “Wind Tunnel        Off” on the HMI.    -   c. The PLC will close a contact illuminating Red LED strip on        the wind tunnel.    -   d. Category 1 Emergency Stops activate two (2) safety relays        located in the bottom of the control console in the following        sequence.        -   i. Initially, the activation of the Emergency Safety Timing            Relay, ESTR, directly and not through the PLC, commands the            VFD to reduce the speed of the motor at the rate configured            during commissioning and activates the Emergency Safety            Timing Relay.        -   ii. When the Emergency Safety Timing Relay times out, the            contacts monitored by the “Safe Torque Off” DIs in the VFD            will open. At this point, the VFD disables the internal            control voltage of the power semiconductors of the VFD            output stage to the motor. The motor will coast to a stop.            Refer to Safe Torque OFF Section V below.    -   e. “Wind Tunnel Fault” replaces “Wind Tunnel On” or “Wind Tunnel        Off” on the HMI.    -   f. The PLC opens the DO contact connected to the VFD Start/Stop        DI.    -   g. After pulling out the Emergency Stop Pushbutton or correcting        the issue that caused the alarm, a “Reset” pushbutton appears on        the HMI.    -   h. If an instrument in the lube oil systems caused the emergency        stop, the PLC opens the DO contact within the 24 Volt AC run        circuit of the Gearbox Lube Oil Pump's combination starter.        Otherwise, if the “Reset” pushbutton is not pushed, the PLC will        wait five minutes after the initiation of the Category 1        Modified Emergency Stop, before opening the contact within the        24 Volt AC run circuit of the Gearbox Lube Oil Pump's        combination starter.    -   i. If the “Reset” pushbutton is not pushed, the PLC opens the DO        contact within the 24 Volt AC run circuit of the Equipment Pit        Exhaust Fan's combination starter 20 minutes after the        initiation of the Category 1 Modified Emergency Stop.    -   j. Press the “Reset” pushbutton on the HMI and follow Section        II-C above to restart the wind tunnel.

Gearbox Lube Oil System

-   -   A. The PLC monitors the Low Flow Switch 1732, High Flow Switch        1734, Low Pressure Switch 1712 and High Temperature Switch 1724        in the Gearbox Lube Oil System.    -   Commencing one minute after the PLC closes the DO that starts        the Lube Oil Pump, if the Low Flow Switch, the High Flow Switch,        the Low Pressure Switch or the High Temperature Switch open,        indicating that the oil is not pumping properly, the PLC will        initiate a Category 1 Modified Emergency Stop.    -   B. The PLC monitors auxiliary contacts on the Lube Oil Pump        Starter and the Lube Oil Fan Starter. If the PLC detects an        unexpected opening of the starters' auxiliary contacts, the PLC        will initiate a Category 1 Modified Emergency Stop.    -   C. Leak detection sensors are located in the oil containment        pans below the Oil Lube Oil Skid and at the bottom of the        nacelle below the 2.5:1 gearbox.    -   D. The PLC monitors the sensors. When activated, the PLC will        display a warning on the HMI and will not permit starting the        tunnel.

Inspections and Maintenance

Safe Torque Off

-   -   a. The VFD has a Safe Torque Off feature that “enables        short-time maintenance operations like cleaning or working on        non-electrical parts of the machinery without opening the 800        Amp Service Entrance Disconnect switch.    -   b. When activated, the Safe Torque Off function disables the        control voltage of the power semiconductors of the VFD output        stage, thus preventing the VFD from generating the torque        required to rotate the motor. If the motor is running when Safe        Torque Off is activated, the motor coasts to a stop.    -   c. Open, lock out, and tag out the local “Safe Torque Off”        Disconnect Switch before inspecting or maintaining the 500 HP        motor or fan.    -   d. The Safe Torque Off circuit has been designed with a Safety        Integrity Level (SIL) of 2.    -   e. When the VFD Safe Torque Off is enabled, the motor will        immediately coast to a stop and the VFD will open the “VFD        Enable” contact, which connects to the PLC “Run Enable” DO.    -   f. The PLC will display “Safe Torque Off” on the HMI screen. No        one should open the motor terminal box, work on the drive train        or work on the fan unless “Safe Torque Off” is displayed on the        HMI and the Safe Torque Off Switch is open, locked out ad        tagged.    -   g. During maintenance within the Equipment Pit, move the        Selector on the Equipment Pit Exhaust Fan Combination Starter        from the “Auto” to the “On” position to provide ventilation in        the equipment pit.    -   h. The Safe Torque Off control stations include:        -   i. On and Off Selector Switch        -   ii. Green—Safe Torque OFF Pilot light that illuminates when            the equipment can be maintained            Red—Safe Torque OFF Pilot light that illuminates when the            equipment cannot be maintained.

Tunnel Monitoring

A. Located in the equipment pit, Pressure Switch 1712 monitors thepressure after the fan at the bottom of the wind tunnel. The PLCmonitors a normally closed contact in the Pressure Switch. When thecontact opens, indicating that there is high pressure, the PLC initiatesa Category 1 Emergency Stop as described above.B. A set of air taps located around the nozzle connects to aDifferential Pressure Transducer, 5401 using plastic tubing. TheDifferential Pressure Transducer, 5401, located in the bottom of thecontrol console, sends a 4-20 ma value to the PLC AI. The PLC willcalculate the air speed in miles per hour using this value and willdisplay the air speed on the HMI. The PLC will cause a “Nozzle HighDifferential Pressure Alarm” alarm on the HMI when the differentialpressure value is too high and activated a Category 1 Emergency Stop.C. A set of air taps located around the wind tunnel connects to aDifferential Pressure Transducer, using plastic tubing. The DifferentialPressure Transducer, located in the bottom of the control console, sendsa 4-20 ma value to the PLC AI. The PLC will display the value of thedifferential pressure across the fan on the HMI. The PLC will cause a“Fan High Differential Pressure Alarm” alarm on the HMI when thedifferential pressure value is too high and activated a Category 1Emergency Stop.D. The PLC monitors a High Temperature Switch in the nacelle. Whenactivated, the PLC will cause a “Nacelle High Temperature” alarm on theHMI activated a Category 1 Emergency Stop.E. The PLC monitors a Temperature Transducer 5101. When the airtemperature reaches a high level, the PLC will cause an “Equipment PitHigh Temperature” alarm on the HMI activated a Category 1 ModifiedEmergency Stop.F. The PLC monitors a Temperature Transducer 5101. The PLC also usesthis value to calculate the air speed. When the temperature reaches ahigh level, the PLC will cause a “Wind Tunnel High Temperature” alarm onthe HMI activated a Category 1 Emergency Stop.

Equipment Monitoring

A. Motor Overload Protection—Connected in series, NC contacts forthermistors that monitor the stator windings of the 500 HP motor foroverload, connect directly to the VFD. When a thermistor contact opens,the VFD will initiate a Category 1 Emergency StopB. Motor Vibration Protection—The PLC monitors the 500 HP motor's driveend Horizontal Vibration Transmitter and Vertical Vibration Transmitter

-   -   a. Vibration transmitters send 4-20 ma values to PLC Als.    -   b. When the vibration level on either transmitter reaches the        high vibration value stored in the PLC, the HMI will display a        “High Motor Vibration” warning.    -   c. When the vibration on either transmitter reaches the        high-high vibration value stored in the PLC, the HMI will        display a “High High Motor Vertical Vibration” or “Motor High        High Horizontal Vibration” alarm and the PLC will initiate a        activated a Category 1 Emergency Stop.        C. Gearbox Vibration Protection—The PLC monitors the gearbox's        Output Horizontal Vibration Transmitter, Output Vertical        Vibration Transmitter and the Input Vibration Transmitter.    -   a. Vibration transmitters send 4-20 ma values to PLC Als.    -   b. When the vibration level on any of the transmitters reaches        the high vibration value stored in the PLC, the PLC will cause a        “High Gearbox Output Horizontal Vibration”, a “High Gearbox        Output Vertical Vibration” or a “High Gearbox Input Vertical        Vibration” warning on the HMI.    -   c. When the vibration on any of the transmitters reaches the        high-high vibration value stored in the PLC, the PLC will cause        a “High High Gearbox Output Horizontal Vibration”, a “High High        Gearbox Output Vertical Vibration” or a “High High Gearbox Input        Vertical Vibration” alarm on the HMI and activated a Category 1        Emergency Stop.        D. VFD—The PLC monitors the VFD Fault contact. If the fault is        severe, the PLC will activate a Category 1 Emergency Stop or the        VFD will cause a Safe Torque Off resulting in a Category 0        Emergency Stop.        E. Access Doors—Normally Open Magnetic switches monitor the        access door to the electrical room where the Service Entrance        Disconnect Switch and the VFD are located and the access door to        the equipment area and pits where the “Safe Torque Off” switches        are located. The HMI will display a warning when any of the        switches are closed.

Tunnel Hatches—Normally Open Magnetic Switches monitor the tunnelhatches. The switches must be open to start the wind tunnel. The HMIwill display a warning when any of the switches close during operation.

PLC monitors auxiliary contacts on the local disconnect switches for theLube Oil Pump, the Lube Oil Fan and the Exhaust Fan Local DisconnectSwitch. When the switches are open, the PLC will display a warning onthe HMI and will not permit starting the tunnel.

While the foregoing invention has been described with reference to theabove-described embodiment, various modifications and changes can bemade without departing from the spirit of the invention. For example,while embodiments of the present disclosure illustrate a closed loop,fixed system wind tunnel platform, it is contemplated that embodimentsof the system may implement a single tunnel system where the fan and hubassembly may be positioned in alignment with the flight chamber (e.g.directly beneath). In addition, it is contemplated that a system may beimplemented on a mobile platform. Accordingly, all such modificationsand changes are considered to be within the scope of the appendedclaims. Accordingly, the specification and the drawings are to beregarded in an illustrative rather than a restrictive sense. Theaccompanying drawings that form a part hereof, show by way ofillustration, and not of limitation, specific embodiments in which thesubject matter may be practiced. The embodiments illustrated aredescribed in sufficient detail to enable those skilled in the art topractice the teachings disclosed herein. Other embodiments may beutilized and derived therefrom, such that structural and logicalsubstitutions and changes may be made without departing from the scopeof this disclosure. This Detailed Description, therefore, is not to betaken in a limiting sense, and the scope of various embodiments isdefined only by the appended claims, along with the full range ofequivalents to which such claims are entitled.

Such embodiments of the inventive subject matter may be referred toherein, individually and/or collectively, by the term “invention” merelyfor convenience and without intending to voluntarily limit the scope ofthis application to any single invention or inventive concept if morethan one is in fact disclosed. Thus, although specific embodiments havebeen illustrated and described herein, it should be appreciated that anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations of variations of various embodiments.Combinations of the above embodiments, and other embodiments notspecifically described herein, will be apparent to those of skill in theart upon reviewing the above description.

What is claimed is:
 1. A flight simulator comprising: a) a wind tunnelchamber comprising a first vertical flight chamber and a second verticalchamber communicatively coupled thereto via air flow conduits; b) anacelle disposed within the second vertical chamber of the wind tunnelchamber and including a ratio gearbox connected to a fan; c) a motordisposed remote from the nacelle for powering the fan via a jackshaftand the ratio gearbox to rotate the fan at least a threshold minimumspeed sufficient to enable human flight within the first vertical flightchamber; d) a variable frequency drive responsive to a control signalfrom a programmable logic controller to regulate the speed of the motorto: a) a first nonzero target motor speed which is not sufficient tocause the fan to rotate at least the threshold minimum speed; or b) arange of second target motor speeds, all second target motor speeds inthe range being greater than the first nonzero target motor speed andsufficiently high to cause the fan to rotate at least the thresholdminimum speed; or c) a third target motor speed of zero RPM indicativeof an off condition; wherein the variable frequency drive is programmedto operate the motor at nonzero target speeds only equal to or greaterthan said first nonzero target motor speed.
 2. The simulator of claim 1,wherein the programmable logic controller is responsive to one or moreenvironmental parameters for generating a control signal to the variablefrequency drive to controllably adjust motor speed.
 3. The simulator ofclaim 1, further comprising a lubrication system disposed remote fromthe nacelle and fluidly coupled to the ratio gearbox via a supplyconduit for controllably dispensing lubricant thereto.
 4. The simulatorof claim 3, wherein the programmable logic controller is responsive toone or more of temperature, pressure, leakage, and flow parametersoutput from the lubrication system for generating a control signal tothe variable frequency device to controllably adjust motor speed.
 5. Thesimulator of claim 1, wherein the variable frequency drive is an IEEE519 compliant VFD which controllably adjusts at least one of frequencyand voltage applied to said motor to operate said motor at one of twopredetermined RPM rates.
 6. The simulator of claim 1, wherein one ormore vibration sensors are positioned about the motor for sensing motorvibration and providing one or more output signals whose amplitudes areindicative of the level of vibration sensed.
 7. The simulator of claim6, wherein the programmable logic controller is responsive to the one ormore output signals of said vibration sensors for generating a controlsignal to the variable frequency drive to stop the motor when the outputsignal amplitude exceeds a predetermined threshold indicative of a highvertical or high horizontal motor vibration level.
 8. The simulator ofclaim 1, wherein the first nonzero target motor speed is 500 RPM.
 9. Thesimulator of claim 1, wherein the ratio gearbox is drive end thrustright angle bearing ratio gearbox.
 10. The simulator of claim 9, whereindrive end thrust right angle bearing ratio gearbox is a 2.5:1 ratio andthe motor connected thereto is a 500 HP, 1800 RPM motor.
 11. A flightsimulator comprising: a) a wind tunnel chamber comprising a firstvertical flight chamber and a second vertical chamber communicativelycoupled thereto via air flow conduits; b) a nacelle disposed within thesecond vertical chamber of the wind tunnel chamber and including a ratiogearbox connected to a fan; c) a motor disposed remote from the nacellefor powering the fan, the motor being connected to the ratio gearbox viaa jackshaft; d) a variable frequency drive configured to regulate thespeed of the motor within a minimum and maximum operation range of themotor; e) a lubrication system disposed remote from the nacelle andfluidly coupled to the ratio gearbox for controllably dispensinglubricant; wherein a programmable logic controller is responsive to oneor more of temperature, pressure, leakage, or flow parameters outputfrom the lubrication system for generating a control signal to thevariable frequency drive to controllably adjust motor speed.
 12. Thesimulator of claim 11, wherein one or more vibration sensors arepositioned about the motor for sensing motor vibration and providing oneor more output signals whose amplitudes are indicative of the level ofvibration sensed.
 13. The simulator of claim 12, wherein theprogrammable logic controller is responsive to the output signals ofsaid vibration sensors for outputting a control signal to the variablefrequency drive to stop the motor when the output signal amplitudeexceeds a predetermined threshold indicative of a high vertical or highhorizontal motor vibration level.
 14. The simulator of claim 11, furthercomprising a return conduit disposed between said ratio gearbox and saidlubrication system for returning used lubricant from said ratio gearbox,and a cooling unit configured to cool the returned lubricant prior torecirculation to said ratio gearbox for maintaining flow and temperatureof the ratio gearbox.
 15. The simulator of claim 11, wherein saidvariable frequency drive receives a control signal from a programmablelogic controller, the variable frequency device is programmed to adjustthe speed of the motor to: a) a first nonzero target motor speed whichis not sufficient to cause the fan to rotate at least a thresholdminimum speed enabling human flight within the tunnel; or b) a range ofsecond target motor speeds, all second target motor speeds in the rangebeing greater than the first nonzero target motor speed and sufficientlyhigh to cause the fan to rotate at least the threshold minimum speed; orc) a third target motor speed of zero RPM indicative of an offcondition, and wherein the variable frequency drive is programmed tooperate the motor at nonzero target speeds only equal to or greater thansaid first nonzero target motor speed.
 16. The simulator of claim 15,further comprising a potentiometer adjustable via a user interfacecoupled to the programmable logic controller sets the second targetmotor speed.
 17. The simulator of claim 11, wherein the variablefrequency drive includes an electronic switch electrically connected tothe programmable logic controller for selectively disabling, in responseto a user operation, a low control voltage of power semiconductors of anoutput stage of the variable frequency drive, to thereby prevent thevariable frequency drive from generating a torque required to rotate themotor, without activation of a high ampere main disconnect switch. 18.The simulator of claim 11, wherein the ratio gearbox is drive end thrustright angle bearing ratio gearbox.